CWSP Guide to Wireless Security Models Objectives Explain

CWSP Guide to Wireless Security Models

Objectives • Explain the advantages of WPA and WPA 2 • Explain the technologies that are part of the personal security model • List the features of the transitional security model • Define the enterprise security model CWSP Guide to Wireless Security 2

Wireless Security Solutions • WEP suffers from serious weakness • “Band-aid” solutions – WEP 2 and Dynamic WEP • Better solutions – IEEE 802. 11 i – Wi-Fi Protected Access (WPA) – Wi-Fi Protected Access 2 (WPA 2) CWSP Guide to Wireless Security 3

IEEE 802. 11 i • Addresses the two weaknesses of wireless networks: encryption and authentication • Encryption – Replaces the RC 4 stream cipher algorithm with a block cipher • Manipulates an entire block of text at one time – 802. 11 i uses the Advanced Encryption Standard (AES) • Designed to be an encryption technique that is secure from attacks CWSP Guide to Wireless Security 4

Block Ciphers vs Stream Cipher • Block ciphers – ie. DES, 3 DES, AES – Message is broken into blocks, each of which is then encrypted – Operate with a fixed transformation on large blocks of plaintext data • Stream ciphers – ie. RC 4 – Process the message bit by bit (as a stream) – Operate with a time-varying transformation on individual plaintext digits

RC 4 • RC 4 was designed by Ron Rivest of RSA Security in 1987, it is officially termed “Rivest Cipher 4”. • RC 4 algorithm is capable of key lengths of up to 256 bits and is typically implemented in 64 bits, 128 bits and 256 bits. • RC 4 is used in WEP, TKIP (Temporal Key Integrity Protocol, (SSL) Secure Socket Layer , (TLS) Transport Layer Security

Encryption Algorithm Characteristics Name Cipher Key Size Type 64, 128 up to 256 bits RC 4 Stream Common Use WEP, WPA (TKIP), SSL/TLS DES Block 64 -bit (56 -bit key + 8 Parity bits) SSH, IPSec 3 DES Block Three-Key Mode: 192 -bit (168 SSL/TLS, SSH, -bit key + 24 Parity bits) IPSec Two-Key Mode: 128 -bit (112 -bit key + 16 Parity bits) AES Block 128, 192, 256 -bits 802. 11 i-CCMP, SSH, PGP

Client Authentication SSL

WEP vulnerabilities, and usage of WPA Cracking WEP and WPA wireless networks and How to Better Secure Wireless Networks

In this section we will discuss • How to crack WEP and WPA • Tactics to better secure your network

WEP cracking • WEP is outdated and week • Novice hackers will hack WEP very easily • WEP uses a 3 -byte vector (IV) Initialization Vector – IV is placed in packets – based on pre-shared key • Capturing thousands of these packets from the client or AP you will have enough data gathered to crack WEP

Tools • Air. Crack, – Aircrack contains several tools • Tools will be using – Airodump – capturing IVs – Aircrack – cracking IVs • Kismet – For sniffing and locating networks

Getting Started • The device (laptop) wireless card must be put into “monitor mode” aka. (promiscuous mode) – allows wireless card to locate and crack wlan network – putting wireless card in this mode is not very easy. Web browsing will not be possible when wireless card is placed in promiscuous mode. – Rollback wireless card drivers to undo monitor mode.

Getting Started – cont. • Run kismet or airodump and locate nearby networks • The info we need: – – Encryption type Channel no. IP address MAC address (BSSID) • Ie. Let’s use a channel 6 – and SSID (MAC address) 00: 23: 1 F: 55: 04: BC

Capturing • Capturing IVs – Use airodump – type command: /airodump <interface> <output prefix> [channel] [IVs flag] • Example – /airodump cardname test 6 1 • “test” is the filename with our captured IVs • “ 1” is always used for IVs flag when cracking WEP • Note: (the more the merrier) meaning: we will need over 100, 000 IVs to crack the WEP key

Airodump or Kismet output 1. BSSID = MAC 2. CH = Channel Number 3. # Data = Number of IVs captured so far

Cracking • Cracking IVs – Using aircrack command: /aircrack [option] <input file> • The options are – -a 1 for WEP – -b for BSSID – (the input file is the file we generated using airdump command earlier) : Ie. /aircrack –a 1 –b 00: 23: 1 F: 55: 04: BC test. ivs

Screenshot from aircrack • Info from airodump is fed into aircrack the program will return the WEP key used on that network. Program gave out over 30566 IVs in 18 seconds. Could do 3000000 in less than 3 min.

WEP finale • The time needed for cracking the WEP key is determined by the number of the IVs collected. • Any number of IVs over 100000 is reasonable and should yield the WEP key within minutes.

Intro to cracking WPA • WPA keys are much harder than WEP to crack • WPA cracking nearly impossible • WPA fills out holes that WEP can’t

Getting started • WPA passwords are real words – dictionary word list

Capturing • Run kismet to gather network info required • Open airodump, enter command: /airodump cardname test 2 – Cardname is the name of the wireless card – Test is the name of the output file – 2 is the channel we retrieved using Kismet

Cracking • Open aircrack and type: /aircrack –a 2 –b 00: 25: 1 G: 45: 02: ad –w/path/to/wordlist – to crack WPA use –a 2 – -b is the MAC (BSSID) – -w is path on your computer to the dictionary word list • If the command yields the WPA passkey you are one lucky hacker. Else you are out of luck. .

Conclusion • WEP is easier to crack than WPA • Air. Crack is one tool used to crack WEP

Reasons you should secure your network • Your resources are exposed to unknown users • Your network can be captured, examined • Your network and connectivity may be used for illegal activities

Countermeasures • Use these tips to prevent unwanted users – Change default setting on your router • When you install router modify id and pwd to something else rather than default – Disable SSID broadcast • Hides network from beginner intruder. Ie. Windows Wireless Zero config utility • Will not keep you safe from more advance hackers – Turn off network when not in use • Impossible to hack a network that it is not running – MAC address filtering • AP grants access to certain MAC addresses • Not fully proof, but good countermeasure – Encryption • Use of WPA • Use long and random WPA keys

IEEE 802. 11 i (continued) CWSP Guide to Wireless Security 27

IEEE 802. 11 i (continued) • Authentication and key management – Accomplished by the IEEE 802. 1 x standard • Implements port security • Blocks all traffic on a port-by-port basis – Until the client is authenticated using credentials stored on an authentication server • Key-caching – Stores information from a device on the network – If a user roams away and later returns • She does not need to re-enter all of the credentials CWSP Guide to Wireless Security 28

IEEE 802. 11 i (continued) CWSP Guide to Wireless Security 29

IEEE 802. 11 i (continued) • Pre-authentication – Allows a device to become authenticated to an AP • Before moving into range of the AP – Device sends a pre-authentication packet to the AP which the user is currently associated with • And the packet is then routed to a remote AP or APs – Allows for faster roaming between access points CWSP Guide to Wireless Security 30

Wi-Fi Protected Access (WPA) • Subset of 802. 11 i • Addresses both encryption and authentication • Temporal Key Integrity Protocol (TKIP) – TKIP keys are known as per-packet keys – TKIP dynamically generates a new key for each packet that is created – Prevent collisions • Which was one of the primary weaknesses of WEP • Authentication server can use 802. 1 x to produce a unique master key for that user session CWSP Guide to Wireless Security 31

Wi-Fi Protected Access (WPA) (continued) • TKIP distributes the key to wireless devices and AP – Setting up an automated key hierarchy and management system • WPA replaces the Cyclic Redundancy Check (CRC) with the Message Integrity Check (MIC) – Designed to prevent an attacker from capturing, altering, and resending data packets – Provides a strong mathematical function – Clients are de-authenticated and new associations are prevented for one minute if an MIC error occurs • Optional feature CWSP Guide to Wireless Security 32

Wi-Fi Protected Access (WPA) (continued) CWSP Guide to Wireless Security 33

Wi-Fi Protected Access (WPA) (continued) • WPA authentication – Accomplished by using either IEEE 802. 1 x or preshared key (PSK) technology • PSK authentication uses a passphrase to generate the encryption key – Passphrase must be entered on each access point and wireless device in advance – Passphrases serve as the seed for mathematically generating the encryption keys • WPA was designed to address WEP vulnerabilities with minimum inconvenience CWSP Guide to Wireless Security 34

Wi-Fi Protected Access 2 (WPA 2) • Second generation of WPA security • Based on the final IEEE 802. 11 i standard • Uses the Advanced Encryption Standard (AES) for data encryption • Supports IEEE 802. 1 x authentication or PSK technology • WPA 2 allows both AES and TKIP clients to operate in the same WLAN CWSP Guide to Wireless Security 35

Advanced Encryption Standard AES ENCRYPTION • Rijndael is the selected (NIST competition) algorithm for AES (advanced encryption standard). • It is a block cipher algorithm, operating on blocks of data. • It needs a secret key, which is another block of data.

AES ENCRYPTION • Performs encryption and the inverse operation, decryption (using the same secret key). • It reads an entire block of data, processes it in rounds and then outputs the encrypted (or decrypted) data. • Each round is a sequence of four inner transformations. • The AES standard specifies 128 -bit data blocks and 128 -bit, 192 -bit or 256 -bit secret keys.

AES Algorithm – Encryption PLAINTEXT encryption algorithm structure of a generic round SECRET KEY ROUND 0 INPUT DATA ROUND KEY 0 SUBBYTES ROUND 1 ROUND KEY 1 SHIFTROWS KEY SCHEDULE MIXCOLUMNS ROUND 9 ROUND 10 ENCRYPTED DATA ROUND KEY 9 ROUND KEY ADDROUNDKEY ROUND KEY 10 OUTPUT DATA

AES Algorithm – Encryption A little closer look 1. Perform a byte by byte substitution 2. Perform a row by row shift operation 3. Perform a column by column transformation 4. Perform a XOR with a round key No of rounds = 10 for 128 bits 12 for 192 bits 14 for 256 bits

AES Advanced Encryption Standard 1. The Sub. Byte Step

AES Advanced Encryption Standard 2. The Shift. Row Step

AES Advanced Encryption Standard 3. The Mix. Columns Step

AES The Add. Round. Key step

Some facts about AES • AES keys (128 bits) 340, 000, 000, 000, 00 0 (3. 4028236692093846346337460743177 e+38) ( possible keys • Suitable for a wide variety of platforms - ranging from smart cards to servers • Much simpler, faster and more secure (than it’s predecessor 3 DES )

AES ‘built-into’ products • Navastream Crypto Phones • PGP Mobile for the TREO 650 • Nokia’s solutions for mobile VPN client – AES 256

AES Cracking - 2006 • Assumptions – 3 GHz dedicated processor – 1 clock cycle per key generation • 2^128 keys / 3 E 9 processes per second = • 1. 13 E 29 seconds • 3. 6 E 21 years, 3. 6 Zy (Zetta years) • 3. 6 Sextillion years

AES Cracking - Future • 1 Week Decryption • 5. 6 E 32 Hz Processor, 560 MHz Clock Cycles per Key Generation Processor Speed Doubling Rate (Years) 1 4 8 16 0. 5 38. 8 155. 3 310. 7 621. 3 1 77. 7 310. 7 621. 3 1242. 6 1. 5 116. 5 466. 0 932. 0 1863. 9 2 155. 3 621. 3 1242. 6 2485. 3

Wi-Fi Protected Access 2 (WPA 2) (continued) CWSP Guide to Wireless Security 48

Wi-Fi Protected Access 2 (WPA 2) (continued) • Wi-Fi Alliance wireless security models based on WPA and WPA 2 – – WPA—Personal Security WPA—Enterprise Security WPA 2—Personal Security WPA 2—Enterprise Security • Transitional security model – Used as a “bridge” solution in situations where WPA or WPA 2 security is not available – Intended as a temporary fix CWSP Guide to Wireless Security 49

Wi-Fi Protected Access 2 (WPA 2) (continued) CWSP Guide to Wireless Security 50

Transitional Security Model • Should only be implemented as a temporary solution CWSP Guide to Wireless Security 51

Authentication • Shared key authentication – Should be used instead of open system authentication – Uses WEP keys for authentication – Based on a challenge-response scheme • SSID beaconing – Should be turned off – May prevent a “casual” unauthorized user or novice attacker from capturing the SSID • And entering the network – Use a hard-to-guess SSID in a WLAN CWSP Guide to Wireless Security 52

Authentication (continued) • MAC address filtering limitations – Managing a large number of MAC addresses is difficult – Does not provide an easy means to temporarily allow a guest user to access the network – WLANs initially exchange MAC addresses in cleartext – A MAC address can be “spoofed” or substituted • DHCP restrictions – DHCP “leases” IP addresses to clients to use while they are connected to the network CWSP Guide to Wireless Security 53

Authentication (continued) CWSP Guide to Wireless Security 54

Authentication (continued) CWSP Guide to Wireless Security 55

WEP Encryption • Should be turned on – If no other options are available for encryption • The longest WEP key available should be used for added security – Most vendors have the option of a 128 -bit WEP key • There is evidence that WEP passphrase generators may create predictable keys CWSP Guide to Wireless Security 56

WEP Encryption (continued) CWSP Guide to Wireless Security 57

Summary • Additional security solutions – IEEE 802. 11 i – Wi-Fi Protected Access (WPA) – Wi-Fi Protected Access Version 2 (WPA 2) • IEEE 802. 11 i standard provided a more solid wireless security model – Uses AES and IEEE 802. 1 x port security • WPA is a subset of 802. 11 i and addresses both encryption and authentication – Uses Temporal Key Integrity Protocol (TKIP) and a Message Integrity Check (MIC) CWSP Guide to Wireless Security 58

Summary (continued) • The transitional security model should be implemented only as a temporary solution CWSP Guide to Wireless Security 59